The bulk of the cornea is made from collagen fibres which are arranged in bundles. The strength and rigidity of the cornea is partly determined by how strongly these fibres are linked together.
In corneal ectasia, the cornea is weakened either pathologically (e.g. keratoconus, pellucid marginal degeneration and keratoglobus) or iatrogenically (e.g. post-LASIK corneal ectasia), causing its shape to become steep and irregular. This weakened cornea can be strengthened with an innovative noninvasive treatment called corneal collagen crosslinking (CXL), where the corneal surface is denuded of the most superficial layer of cells on the cornea (epithelium) and soaked with topical Riboflavin (Vitamin B2) eyedrops. The Vitamin B2 treated cornea is exposed to ultraviolet light which crosslinks and bonds adjacent corneal collagen fibres to strengthen the weakend cornea.
It has been found that CXL has been able to stabilise the corneas in keratoconic patients, as well as patients with post-LASIK ectasia. CXL treatment has managed to improve the corneal topography, astigmatism and visual acuity of many of these unfortunate patients. In addition, CXL has also allowed a limited excimer laser correction of residual myopia and astigmatism in patients suffering from ectasia. Full corrective refractive surgery may not be possible, however the main aim of this type of surgery is to create a more regular and less distorted cornea through custom ablation.